Ser. No. 08/863,335 now U.S. Pat. No. 5,972,926, discloses the preparation of metal alloy powders or granules and their use in decomposing or immobilizing organic compounds containing at least one hetero atom. The present invention is directed to the additional step of coating the metal alloy particles with an organic barrier layer. More specifically, a predetermined combination of processes selected from the group consisting of evacuation, heating, hydrogen exposure and oxygen exposure can be used to activate and prepare a metal alloy powder prior to exposing the powder to a monomer, oligomer, polymer or other organic compound. The monomer, oligomer, polymer or other organic compound directly reacts with or undergoes a reaction catalyzed by the prepared metal alloy in such a way so as to produce a layer of organic material that either physically or chemically adheres to or combines with the metal alloy particle surface.
The metal alloys comprise at least two metals selected from the group consisting of transition metals, alkaline metals, and rare earth metals. The present invention also provides the means by which the metal alloys can be prepared and used to decompose or immobilize harmful chemicals without having the side effect of being harmful or otherwise reactive by contact.
We have also discovered that additional metal alloys selected from the groups of alkali metals (e.g., Na and Li) and metalloids (e.g., Si, B, and Al), can equally be utilized in the present invention to yield powders coated with organic monomers, oligomers, polymers, or other organic compounds.
The present invention therefore relates to the preparation of metal powders or granules and coating thereof with an organic compound, and the subsequent use of the coated metal powders or granules to decompose and immobilize organic wastes containing at least one hetero-atom, for example, halogenated solvents and chemical warfare agents.
Prior art in the coating or encapsulation of metals and other powders include the coating of NaHCO.sub.3 particles disclosed in U.S. Pat. No. 5,482,702 for use in anti-perspirants. U.S. Pat. No. 5,472,661 discloses the process whereby a larger metal powder is spray coated with a finer powder containing a polymer binder. Metal oxides and carbonates have also been encapsulated by radiation-induced vapor phase polymerization at 25-65.degree. C. with vinyl monomers as disclosed in Bruk and Kirpikov, A Method for Encapsulation of Powders by Vapor-Phase Polymerization, 57 Colloid Journal No. 2 (1995). Ono and Takahashi, Chemical Abstract 1990:8195, discloses the spontaneous polymerization of methyl methacrylate in the presence of Cu, Al or Ni powders. Matsumura and Nakabayashi, Adhesive 4-META/MMA-TBB Opaque Resin with Poly(methyl methacrylate)-coated Titanium Dioxide, J. Dent. Res. 67(1):29-32 (1988) discloses the coating of TiO.sub.2 particles by aqueous phase polymerization of methyl methacrylate. Yamaguchi et al., Coating of metal powder surface with polymethyl methacrylate, 17 Chem. Ind. 748 (1975) discloses the polymerization of methyl methacrylate onto Al, Fe, Cu, or Ag surfaces in aqueous SO.sub.2.
A comprehensive discourse of prior art related to metal and metal alloy catalysts is given in incorporated Ser. No. 08/863,335 which details the usefulness of activating metal alloy materials so as to increase their reactivity and to decrepitate the materials to finer scale powders, leaving the materials in a reactive state that is in the form of an oxide, hydride, or reduced metal. A reduced metal state hereby refers to an instance whereby the final process step is evacuation or evacuation with heating so that the metal alloy is considered neither oxide nor hydride and the metal exists in an elemental state.
An object of the present invention is to produce coated metal alloy powders or granules by contacting the metal alloy powders or granules, activated in a manner described by U.S. Pat. No. 5,922,926, with a monomer, oligomer, polymer, or other organic compound in a liquid or vapor state. The organic compound can also exist as a solid at room temperature and, when mixed and then heated with the metal alloy material, it undergoes a phase change to a liquid and/or vapor form and reacts with the metal alloy material.
Another object of the present invention is to carry out the metal alloy particle coating process without an aqueous phase or other solvent. Thus, the process involves the use and direct contact of a monomer, oligomer, polymer, or other organic compound with the metal alloy particle in an activated state.
Another object of the present invention is to use the coated metal alloy particles for decomposing or immobilizing chemicals containing at least one hetero-atom.
The present invention also provides a reactive metal alloy substrate that is not reactive to physical contact due to the presence of the coating material, which serves as a barrier between the physical contact and the reactive metal alloy material.